1. Field of the Invention
The present invention relates generally to the field of automatic guns and more particularly to the field of large calibre, externally-powered guns or cannon.
2. Discusson of the Prior Art
Many types of automatic guns, ranging in size from small calibre submachine guns to large calibre anti-aircraft and anti-tank guns, are used by the military. These automatic guns can be generally classified, according to their mode of operation, as either self-powered or externally powered. As implied, self-powered automatic guns utilize recoil or high pressure barrel gasses caused by firing to cycle operating mechanisms which load and fire the gun. In contrast, operating mechanisms of externally-powered guns are driven by actuators or motors independently of firing forces.
Self-powered automatic guns are inherently more portable or mobile than externally-powered guns and are, therefore, usually preferred for small arms, machine guns and light cannons, such as typically also being comparatively easy to implement as self-powered guns. For larger cannons, the associated weapons systems typically must provide auxiliary power for gun aiming movement. As a result, the providing of external power also to operate the gun itself is usually not a great disadvantage. Since such larger guns are difficult to implement as self-powered guns, because of shell size and weight and massiveness of moving operational parts, larger guns have typically been constructed to be external powered.
In the intermediate, approximate 20 through 40 mm cannon size range, some automatic guns are constructed as self-powered and others as externally powered, depending on specific system and performance criteria. For example, if auxiliary gun-operating power can be provided at no great sacrifice of gun size or weight, externally-powered guns may be preferred because of their potentially greater firing rates. On the other hand, if size constraints and weapons system mobility are important, self-powered guns are usually preferred.
Large guns, that is, those of about 75 mm calibre and larger, have typically been found very difficult to fully automate, even by use of external power. This is because the shells are large and cumbersome and the guns themselves are massive. In particular, automation of such large guns for operational use in the tight confines of armored vehicles has been especially difficult because of space limitations.
As a result, automation of all large guns in general, and of those used in tanks and armored vehicles in particular, has heretofore usually been limited to the automation of single operational functions, for example, opening and closing the breech or loading shells into an open breech. A human operator has ordinarily functioned to operationally bridge the separately automated functions. Firing rates of such guns, in which an operator performs the key role as system integrator, have thus been limited by the operator's skill and ability in perceiving the operational status of the automated gun hardware and in deciding when the operating commands should be given to initiate each successive automated operation.
Many problems encountered in mechanizing large guns are believed attributable to the fact that the guns were not originally designed for automatic operation. Thus, design of such guns has principally involved adaptations of pre-existing, manually operated guns. As a consequence, their automation has usually consisted of little more than the retrofitting of existing gun hardware. Although some limited success has been achieved through such retrofitting, the resulting gun systems have, at best, been awkward and non-optimal in terms of gun operating speeds and firing rates, and also in terms of system cost and reliability. These retrofit-type gun systems have, therefore, usually had little appeal to intended military customer and so far as is known to the applicants, none has ever been put into production.
Moreover, control systems for such previously automated large calibre guns have to applicants' knowledge, heretofore controlled only a few sequential steps and have been implemented by simple AND or OR logic elements, flip-flop circuits typically being used to control actuating motors or solenoids. Also, the progression from one separately automated step to another has heretofore been sequenced by pre-set timers, so that gun operation proceeds in accordance with a fixed time schedule. Reliance upon such timing schedules, however, can cause serious problems because operating times may, in fact, vary widely in the same gun according to conditions. For example, the time required to advance shells to the gun typically varies according to the number, and hence the mass, of shells which must be advanced. Operating times also depend upon such factors as how clean or how well lubricated the gun is, the extent of gun wear and the operating temperatures. If the gun design does not take such time-affecting variables into consideration, one operating step may be initiated before a preceding step is completed, with potentially disastrous consequences.
A particular event which is difficult to provide for in a fixed timing schedule is shell firing time. Typically shells fire within a few milliseconds after firing impact or, as the case may be, electrical contacting. Propellant combustion ordinarily occurs within the next few milliseconds and casing pressure is typically reduced to a safe casing extraction level in several more milliseconds. Thus, only about 10 to 20 milliseconds of firing "dwell time" is ordinarily required.
However, in system use, some few shells, presumably due to manufacturing defects, do not fire as expected. Instead, there is a brief delay after impact or electrical contact before ignition occurs. This phenomenon is commonly referred to as a "hang fire" condition. If a hang fire causes a shell to fire after a timed casing extraction has begun, the gun may be destroyed and operating personnel may be injured. On the other hand, if worst case hang fires are considered in establishing the gun operating time schedule, gun performance will be compromised. If the timing schedule also takes into account all other possible worst case conditions affecting gun operating times, the firing rate will be drastically reduced over that possible under most operating conditions. As a result, the automatic operation of a gun on a fixed timing schedule is generally unsatisfactory.
It is, therefore, an object of the present invention to provide an externally-powered, automatic gun system in which operation of the gun does not proceed on a fixed time schedule.
Another object of the present invention is to provide an externally-powered, automatic gun system in which the initiation of any operational step in a sequence of operating steps is conditioned upon the proper completion of the preceding operational steps.
Still another object of the present invention is to provide an externally-powered automatic gun system in which the operating times of at least some of the operational steps are measured and are compared with pre-established operating times, and in which operation of the gun is stopped if any of the pre-established operating times are exceeded.
A further object of the present invention is to provide an externally-powered automatic gun system which operates on a strict logic basis, rather than on a fixed timing schedule and which stops operating if pre-established logic conditions are not met and which, moreover, provides status and malfunction information to the gun operator.
Another object of the present invention is to provide an externally-powered, automatic gun system in which initiation of each operational step is conditioned on specific moving parts of the gun being in specific positions.
Yet another object of the present invention is to provide an externally-powered automatic gun system whose operating system provides failure predictions based, at least in part, upon operating times of moving parts of gun system.
Other objects, features and advantages of the present invention will be readily apparent from the following detailed description when taken in conjunction with the accompanying drawings.